Had Hitler succeeded in his plan to invade Britain the world would now be a very different place. The United States would probably have remained neutral, leaving Germany, Italy and Russia to carve up Europe between them. There was just the small matter of destroying the Royal Air Force...

By July 1940, German forces had occupied France, Belgium, Denmark, Norway and the Netherlands. Hitler’s troops now stood a mere 21 miles from the English coast and had direct access to the Atlantic Ocean for their submarines to prey on British merchant shipping vital to the island’s survival.

Hitler assumed that with the defeat of her mainland allies, Britain could not continue to fight and would sue for peace. He is said to have had some admiration for Britain and her Empire and made several peace overtures to the British government. When these were rejected he ordered Admiral Raeder, head of the Kriegsmarine, to formulate plans for an invasion. Unlike the earlier successes on the mainland however, this invasion would need to be seaborne and the German navy set out a number of prerequisites necessary to success.

These were the sealing off of all Royal Navy forces from the landing area and the destruction of the Royal Air Force, the clearing of all mines at the crossing points and the Straits of Dover to be blocked at both ends by German mines. The Wehrmacht and the Luftwaffe had both drawn up plans in anticipation of the invasion, with neither of them being very confident of a successful outcome. Herman Goering, head of the Luftwaffe noted that, “a combined operation, having the objective of landing in England must be rejected. It could only be the final act of an already victorious war against Britain as otherwise the preconditions for success would not be met”.

Nevertheless, on the 16th of July 1940, Hitler issued Directive no 16, setting in motion plans for invading Britain, codename “Operation Sea Lion”. He prefaced the order by stating, “As England, despite her hopeless military situation, still shows no signs of coming to terms, I have decided to carry out a landing operation against her. The aim of the operation is to eliminate the English Motherland as a base from which the war against Germany can be continued and, if necessary, to occupy the country completely”.

This was the moment when Britain truly stood alone. Western Europe had been overrun by the Germans and it was only two months since Britain had managed to extricate the remnants of her retreating forces from Dunkirk. Some 330,000 British and Allied soldiers had been lifted from the French beaches, leaving behind huge stores of equipment, trucks and weapons. The army desperately needed time to regroup and rearm. Only the Royal Navy and Royal Air Force were in any condition to oppose an invasion. The RAF fighter strength at the outbreak of war was around 675 aircraft against Germany’s 2000. Despite losses, by August the RAF had 615 Hurricanes and 326 Spitfires in operation as Britain geared up fully for war production.

The ultimate responsibility for Sea Lion was given to Raeder and Goering, neither of whom had much enthusiasm for the task. The Luftwaffe had so far, been fairly ineffective against naval targets, as witnessed in the Norwegian Campaign where, despite air superiority, they managed to sink only two British destroyers. They had not been trained for sea warfare and lacked armour piercing bombs and aerial torpedoes, essential when attacking large warships.

The Kriegsmarine had also suffered heavy losses in this campaign. Two cruisers and ten destroyers had been sunk and others damaged by the British, these being the very ships most suited to protect the invasion forces in the narrow and relatively shallow waters of the English Channel. The heavier battleships and battle cruisers of the German navy had been deployed into the North Atlantic as raiders and would not be available for the operation.

The British navy, despite having much of the fleet engaged in the Atlantic and the Mediterranean, still had superiority in numbers over their foes, particularly in small fast Motor Torpedo Boats which, if allowed, could wreak havoc among the landing barges and escorting warships. Britain had over 700 of these vessels, making them a critical threat if the Luftwaffe could not neutralise them. Tellingly, throughout the war, only nine MTBs were lost to air attack out of the 115 total losses and in the whole of 1940, only nine British destroyers were sunk out the 100 stationed in home waters at the time, five of these being sunk while withdrawing troops from Dunkirk.

It was quite clear to the German High Command that the RAF would have to be neutralised before any landing could be considered and from the middle of July through to August 11th, the first phase of the battle, called Kanalkampf (Channel Battle) by the Germans, opened with German bombers, with fighter escorts, attacking British convoys in the English Channel. The need for constant air patrols over the convoys put severe strain on both pilots and machines of the RAF and, being outnumbered, suffered heavy losses as did the Germans. During this phase of the battle, the RAF suffered losses of 148, while the Luftwaffe lost 248. The fighting did however, give both sides some experience of air to air combat and also confirmed that certain aircraft such as the British Bolton Paul Defiant and the German Bf 110 were unsuitable for intense dogfighting and were withdrawn.

The second phase, codenamed Adlerangriff (Eagle Day) by the Germans, began on the 12th of August when a specialist fighter bomber unit attacked four British radar stations in an attempt to “blind” Fighter Command. They failed to follow up the attack however and the stations were back on line within six hours. If they had persisted in their attacks on these stations or the infrastructure that supported them, the outcome might have been very different.

The next day started with major attacks on coastal airfields used by the RAF as forward landing grounds and on satellite airfields such as Manston and Hawkinge. An indication of the scale of the fighting can be gleaned from the events of the 13th of August when the Luftwaffe flew 1485 sorties, losing 39 planes against British losses of 15. The attacks continued throughout the week, steadily moving inland to airfields around London. The 15th of August saw what the Germans called “The Greatest Day” and launched over 1,000 bombers against England, attacking both the South of England and the North where it was thought English defences were weaker. Although much damage was caused, the attackers suffered heavy losses, particularly in the North where the raiding force of 65 Heinkel 111s, escorted by 35 Bf110s were badly mauled by the fighters. Total German losses for the day were 76 against a British loss of 35 fighters.